First, how many watts....being that it's coralife, it's probably an aqualight and therefore adequate.
Second, how deep is your substrate? My substrate is about 3" deep and with this my Indica has no problems staying rooted.
Thirdly, as Bk mentioned, tall stem plants, especially indica, tend to shed their lower leaves as they get taller because the top of the plant blocks out all of the light from the lower plants. So far I haven't really been able to do anything about this in my own tank. I thinked out the density of the stems and that helped a little, but I found that if I'm using R. indica as a background plant, and letting it get 18"+, then I just have to plant a midground plant or hardscape in front of the lower third to hide the shedding.
And last, roots shooting off from the stem generally indicates a deficiency of one of your macro nutrients, N, P,or K. The plant is looking for one of more of those. If your lighting is as high as I think it is, you should be adding nutrients to the water column in addition to using the flouite substrate. This is probably where your root issues are coming from.